1. Field of the Invention
This invention relates to a recording method and a recording apparatus using the step of communicating an air bubble formed by the utilization of heat energy with the atmosphere, and particularly to a liquid discharging head having a movable member displaceable by the utilization of the creation of an air bubble, a head cartridge using the liquid discharging head, and a liquid discharging device.
This invention can be applied to an apparatus such as a printer for effecting recording on paper, yarn, fiber, cloth, leather, metals, plastics, glass, wood, ceramics or the like as a recording medium, a copying apparatus, a facsimile apparatus having a transmitting system or a word processor having a printer portion, or further an industrial recording apparatus compositely combined with various processing apparatuses.
The term "recording" in the present invention means not only imparting an image having a meaning such as characters or figures to a recording medium, but also imparting an image having no meaning such as a pattern to the recording medium.
2. Related Backgound Art
There is known an ink jet recording method, i.e., a so-called bubble jet recording method, of imparting energy such as heat to ink to thereby create a state change accompanied by a step volume change (creation of an air bubble) in the ink, discharging the ink from a discharge port by an acting force based on this state change, and causing the ink to adhere onto a recording medium to thereby effect image formation. In a recording apparatus using this bubble jet recording method, as disclosed in U.S. Pat. No. 4,723,129, etc., there are generally disposed a discharge port for discharging the ink, an ink flow path communicating with this discharge port, and an electro-thermal converting member as energy generating means for discharging the ink disposed in the ink flow path.
According to such a recording method, images of high quality can be recorded at a high speed and with low noise, and in the head carrying out this recording method, discharge ports for discharging the ink can be disposed at high density and therefore, there are many excellent advantages including the advantage that recorded images of a high degree of resolution, and further color images can be easily obtained by a compact apparatus. Therefore, this bubble jet recording method has recently been utilized in many office instruments such as printers, copying apparatuses and facsimile apparatuses and further, even in industrial systems such as textile printing apparatuses.
As the bubble jet technique is utilized in many fields of products, the following requirements have further heightened in recent years.
For example, as the study on the requirement of an improvement in energy efficiency, mention is made of the optimization of a heat generating member such as adjusting the thickness of protective film. This technique is effective in improving the efficiency of propagation of generated heat to liquid.
Also, there has been proposed a driving condition for providing a liquid discharging method or the like which is high in ink discharge speed and which can effect good ink discharge based on the stable creation of an air bubble, and there has also been proposed an apparatus in which from the viewpoint of high-speed recording, the shape of a flow path is improved to obtain a liquid discharge head which is high in the refill speed of discharged liquid into a liquid flow path.
Of this shape of the flow path, what is shown as flow path structure in FIGS. 18A and 18B of the accompanying drawings is described in Japanese Laid-Open Patent Application No. 63-199972, etc. The flow path structure and head manufacturing method described in this publication are inventions having paid attention to a back wave created with the creation of an air bubble (pressure travelling in a direction opposite to the direction toward a discharge port, i.e., pressure travelling toward a liquid chamber 1012). This back wave, which is not energy travelling in the discharge direction, is known as loss energy.
The invention shown in FIGS. 18A and 18B discloses a valve 1010 spaced apart from an area in which an air bubble is formed by a heat generating element 1002 and located on the opposite side from a discharge port 1011 with respect to a heat generating element 1002.
In FIG. 18B, this valve 1010 is disclosed as one having an initial position like sticking on the ceiling of a flow path 1003 by a manufacturing method utilizing a plate material or the like, and hanging into the flow path 1003 with the creation of an air bubble. This invention is disclosed as one which controls a part of the above-described back wave by the valve 1010 to thereby suppress energy loss.
In this construction, however, as can be seen from the study of the time when an air bubble is created in the flow path 3 holding the liquid to be discharged, it is seen that it is not practical to liquid discharge to suppress a part of the back wave by the valve 10.
Originally the back wave itself is not directly concerned in discharge as previously described. At a point of time whereat this back wave has been created in the flow path 3, as shown in FIG. 18A, the pressure of the air bubble which is directly concerned in discharge already makes the liquid dischargeable from the flow path 3. Accordingly, it is apparent that even if a part of the back wave is suppressed, it will not greatly affect discharge.
On the other hand, in the bubble jet recording method, heating is repeated with a heat generating member being in contact with ink and therefore, a deposit due to the scorching of the ink is created on the surface of the heat generating member. However, this deposit is much created depending on the kind of the ink. When this is created, the discharge of the ink becomes unstable. In addition, in the case of a liquid in which the liquid to be discharged is liable to be deteriorated by heat or a liquid of which the bubbling is difficult to obtain sufficiently, there has been desired a liquid which is not changed in quality but is discharged well.
A method of making a liquid creating an air bubble by heat (bubbling liquid) and a liquid to be discharged (discharge liquid) discrete from each other, and transmitting the pressure by bubbling to the discharge liquid to thereby discharge the discharge liquid is disclosed in publications such as Japanese Laid-Open Patent Application No. 61-69467, Japanese Laid-Open Patent Application No. 55-81172 and U.S. Pat. No. 4,480,259. These publications adopt a construction in which ink which is the discharge liquid and the bubbling liquid are completely separated from each other by flexible film such as silicone rubber so that the discharge liquid may not directly contact with a heat generating member, and the pressure by the bubbling of the bubbling liquid is transmitted to the discharge liquid by the deformation of the flexible film. By such a construction, the prevention of a deposit on the surface of the heat generating member, an improvement in the degree of freedom of selection of the discharge liquid, etc. are achieved.
However, in the head wherein the discharge liquid and the bubbling liquid are completely separated from each other as previously described, the pressure during bubbling is transmitted to the discharge liquid by the expansion and contraction of the flexible film and therefore, the flexible film considerably absorbs the pressure by bubbling. Also, the amount of deformation of the flexible film is not very great and therefore, the effect by separating the discharge liquid and the bubbling liquid from each other can be obtained, but the energy efficiency and the discharging force are reduced.